Rust preventing turbine oil



Patented Feb. 4, 1947 TE FlCE RUST PREVENTING TURBINE H4 No Drawing.Application March 15, 1944,

Serial No. 526,654

3 Claims.

This invention relates to lubricating oil compositions and moreparticularly to a mineral lubricating oil which resists rust formationon iron and steel surfaces in the presence of water and is especiallyfree from the tendency to form emulsions in the presence of water.

Oils used for the lubrication of steam turbines and other machinerywhich is much in contact with water may successfully be treated with certain rust preventing agents, such as metallic naphthenates, metallicsulfonates and the like which have the property of causing the metalsurface to be preferentially wetted with the oil instead of water, thuspreventing or substantially reducing the actual contact of the waterwith the metal surface and the ensuing rust formation. An objectionablefeature usually resulting from the use of such compounds is the tendencyof the additives to cause the formation of an emulsion of the oil withthe water, and this is especially objectionable in the lubrication ofsteam turbines. It is highly desirable, therefore, to preparelubricating oil compositions which are free from the emulsion-formingtendency and which at the same time offer substantial resistance to rustformation in the presence of water. In the case of marine turbines theoil should also prevent rusting in the presence of sea water.

The emulsions which may be formed when the blended lubricating oils arebrought into contact with water are of two types, depending upon thetype of corrosion resisting additive which is used. Metallic soaps orsalts containing alkali metals tend to promote the formation ofoil-in-water emulsions, while soaps or salts of the polyvalent metalspromote water-in-oil emulsions. It has been found, in accordance withthe present invention, that when, in addition to the corrosionpreventing compounds, an additional compound is added to the lubricatingoil which is of the opposite emulsion-forming type, it is possible, byproperly adjusting the relative quantities of the two additives, toreduce the emulsion-forming property of the oil blend to a minimum andto produce thereby a blend which is practically non emulsifying. Thatis, if the corrosion resisting agent is of the type which tends to formoil-inwater emulsions, the second additive should be of the type whichtends to form water-in-oil emulsions. Both of these additives may be ofa corrrosion resisting type, and the invention is preferably practicedby using a combination of an alkali metal mahogany sulfonate and apolyvalent metal naphthenate as the rust resisting component of thelubricating oil.

When a turbine oil is to be prepared, the lubricating oil base ispreferably a highly refined oil of from 50 to 1,500 seconds viscosity(Saybolt) at F. However, the invention is not limited to the preparationof turbine oils, but is applicable to lubricants for the bearings ofmachinery which is much in contact with water, such as in paper millsand refrigerating equipment, as well as to crankcase lubricants, steamengine lubricants, hydraulic fluids, textile oils, cutting oils andinsulating oils, and in general in all cases where a mineral oil is usedunder conditions in which it may pick up or absorb small amounts ofwater from atmospheric condensation or from other sources ofcontamination.

The additives which promote oil-in-water emulsions and possess rustresisting properties include particularly the alkali mahoganysulfonates. Rust resisting additives which tend to form we.- ter-in-oilemulsions include especially the naphthenates of polyvalent metals, suchas calcium, Zll'lC, lead, copper, aluminum, beryllium and relatedmetals. When a rust preventing additive of each of the two types isadded to the lubricating oil, the quantity of each salt is preferablyfrom 0.01% to 1.0% by weight, based on the 111- bricating oil.

The following is an example of the desirable properties which may beobtained by combining two difierent types of metallic soaps in an oilblend in accordance with the present invention.

Example Several blends of sodium mahognany sulfonates and zincnaphthenate in difierent proportions in a highly refined mineral oil ofapproximately 390 seconds viscosity Saybolt at 100 F., and blendscontaining combinations of these additives, were prepared and subjectedto a corrosion test and an emulsion test which will be described below.

The corrosion test employed was the test known as the Navy 2190T SaltWater Corrosion Test (Specification 14-13-15 (INT), F-C(3), March 1,1943) which consisted in suspending a polished steel specimen in amixture of the oil under test with 10% by volume of synthetic sea watercontaining 11 grams of MgC12.6I-I2O, 1.2 grams CaClz, 4.0 grams NazSOaand 25 grams NaCl per liter, and agitating for as hours at 140 F.

The emulsion test employed was the Navy Emulsion Test (FederalSpecification VV-L-791b, Method 320.13, February 19, 1942), whichconsisted in agitating 40 cc. of the oil with 40 cc. of distilled waterat F. to obtain thorough mixing, followed by settling at 130 F. for 30minutes and reading the volume of emulsion remaining after this time, 3cc. or less being considered satisfactory. This procedure was repeatedusing 1% NaCl solution in place of the distilled water.

The results of these tests as applied to the various blends prepared areshown in the following table:

Navy emulsion test (cc. emulsion of- Corro(sdion ter hr.) q test esamplegree of rusting) With dis- With 1% tilled NaCl water solution Mineraloil Heavy 0 Mineral oil+0.02% zinc naphdo .1 0 0 thenate. Mineraloi1+0.05% zinc naph Light 0 0 thenate. Mineral oil-{010% zinc naph-Traee 0 0 thenate. Mineral oil+0.50% zinc naphdo H 28 0 thenatel Mineraloil+0.02% sodium ma- Heavy l l hogany sulfonate. Mineral oil+0.05%sodium ma- Trace... 37 0 hogany sulfonate. Mineral oil+0.l0% sodium ma-Nil 34 3 hogany sulfonate. Mineral oil+0.05% zinc naph- Trace"... 2 0

thenatc+0.02% sodium mahogany sulfonate. Mineral oil+0i05% zine napth-Nil V 0 thenate+0.05% sodium mahogany sulfonate.

The above data show that sea water rusting cannot be stopped by the useof Zinc naphthenate alone in concentrations up to 0.5%, and that when asmuch as 0.5% zinc naphthenate is used the blend is poor inemulsion-forming properties. With sodium mahogany sulfonate alone, seawater rusting can be stopped by the use of 0.1% in the oil, but theemulsion-forming properties are again very poor. The use of 0.05% sodiummahogany sulfonate was not sufiicient to prevent rusting, and even thisquantity produced a large amount of emulsion. The use of the combinationof the metallic soaps gave much better results, and the combination of0.05% of each of the two soaps gave the best results among the blendstested, as the corrosion was entirely prevented and only a very smallamount of emulsion was formed in the distilled water test and none wasformed in the 1% NaCl test.

The oil compositions of the present invention may contain otheringredients in addition to the corrosion resisting metallic salts. Thusthe oils may contain sludge dispersers, thickeners, viscosity indeximprovers, oiliness agents, antioxidants, dyes, etc.

This invention is not to be considered as limited by any of the examplesmentioned or described herein, which are given for illustrative purposesonly, but is to be limited solely by the terms of the appended claims.

We claim:

1. A mineral lubricating oil containing dissolved therein about 0.01% toabout 1.0% of an alkali metal mahogany sulfonate and about 0.01% toabout 1.0% of a polyvalent metal naphthenate, the ratio of thequantities of the two additives being adjusted so that the oil blendexhibits substantially no emulsifying tendency in the presence of water.

2. A mineral lubricating oil containing dis solved therein about 0.05%of sodium mahogany sulfonate and about 0.05% of zinc naphthenate.

3. A mineral lubricating oil composition acaccording to claim 1 in whichthe polyvalent metal naphthenate is zinc naphthenate.

ROBERT K. JOHNSTON. JONES I. WASSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,888,974 Becker Nov. 29, 19322,109,779 Morway Mar. 1, 1938 2,111,907 Zimmer Mar. 22, 1938 2,214,634Dombrow Sept. 10, 1940 2,221,162 Ashburn Nov. 12, 1940 2,308,116Silverman Jan. 12, 1943

